The Science of LifeWhat do biologists do?The Characteristics of LifeMiniLab: Observe Characteristics of LifeAssessment

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 Reading PreviewEssential Questions

What is biology?What are possible benefits of studying biology?What are the characteristics of living things?

Review Vocabularyenvironment: the living and nonliving things that surround an organism and with which the organism interacts

New Vocabularybiologyorganismorganizationgrowthdevelopmentreproductionspeciesstimulusresponsehomeostasisadaptation

 All living things share the characteristics of life.

Real-World Reading Link Think of as many living things as you can. What do oak trees, cheetahs, grass, snakes, planaria, and sharks have in common? What makes them unique? How do we know?

 The Science of LifeBefore Jane Goodall, pictured in Figure 1, arrived in Gombe Stream National Park in Tanzania, Africa, in 1960 to study chimpanzees, the world of chimpanzees was a mystery. Jane's curiosity, determination, and patience over a long period of time resulted in the chimpanzee troop's acceptance of her presence so that she was able to observe their behavior closely.

When people study living things or pose questions about how living things interact with the environment, they are learning about biology, the study of life. Biology comes from the Greek word bio, meaning life, and from logos, meaning study.

In biology, you will study the origins and history of life and once-living things, the structures of living things, how living things interact with one another, and how living things function. This will help you understand how humans have a vital role in preserving the natural environment and sustaining life on Earth.

Have you ever hiked in a forest and wondered why different trees have leaves with different shapes? Maybe you have watched an ant quickly cross the sidewalk toward a breadcrumb and wondered how the ant knew that the breadcrumb was there. When you ask these questions, you are observing, and you are asking questions about life.

Karl Ammann/CORBIS

Figure 1 Jane Goodall conducted field research for many years to observe chimpanzee behavior.

Predict the types of questions you would ask if you observed chimpanzee behavior.

 

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What do biologists do?7.E.i 7.E.iv 11.A more

Imagine being the first person to look into a microscope and discover cells. What do you think it was like to find the first dinosaur fossils that indicated feathers? Who studies how organisms, including the marbled stargazer fish in Figure 2, obtain food? Will the AIDS virus be defeated? Is there life on other planets or anywhere else in the universe? Biologists are people who study biology. They make discoveries and seek explanations by performing laboratory and field investigations. Throughout this textbook, you will discover what biologists in the real world do and you will learn about careers in biology.

Reinhard Dirscherl/Visuals Unlimited

Figure 2 The marbled stargazer fish lives beneath the ocean floor off the coast of Indonesia. It explodes upward from beneath the sand to grab its food.

Observe How does this fish hide from its food?

Study the diversity of lifeJane Goodall, shown in Figure 1, traveled to Africa for the first time in the summer of 1960 to study chimpanzees in their natural environment. By studying chimps in the wild, Goodall witnessed behaviors that had not been observed before. For example, she saw chimps pulling leaves off twigs and using the twigs to retrieve termites from a mound. Before this observation, scientists thought only humans used tools. From her detailed notes, sketches, and maps of chimpanzees' daily travels, Goodall learned how chimpanzees grow and develop and how they gather food. Through Goodall's research we better understand chimpanzees and how to protect them.

Research disease

Mary-Claire King studies chimpanzees from a different perspective. King studies chimpanzee genetics, and in 1973, she established that the genomes of chimpanzees and humans are 99 percent identical. This discovery has changed the field of biology. King's understanding of genetics has led to more research that helps us understand how diseases work and how to treat them.

Many biologists research diseases. Questions such as “What causes the disease?”, “How does the body fight the disease?”, and “How does the disease spread?” often guide biologists' research. Biologists have developed vaccines for smallpox, chicken pox, and diphtheria, and currently, some biologists are researching the development of a vaccine for HIV. Biologists worldwide are researching new treatments for such things as lowering cholesterol levels, fighting obesity, reducing the risk of heart attacks, and preventing Alzheimer's disease.

Develop technologiesWhen you hear the word technology, you might think of high-speed computers, cell phones, and DVD players. However, technology has a broader definition. Technology is defined as the application of scientific knowledge to solve human needs and to extend human capabilities. Figure 3 shows how “bionic” hand technology can help someone who has lost an arm.

Other examples of technology include the work of Charles Drew, a doctor who pioneered methods to separate blood plasma from blood cells and safely store and transport blood plasma for transfusions. His research led to blood banks that saved soldiers during World War II and helps countless patients today.

Biologists today continue to discover new ways to improve and save lives. For example, the field of bioengineering applies knowledge gained from studying the function of living systems to the design of mechanical devices such as artificial limbs. In addition, biologists in the field of biotechnology research cells, DNA, and living systems to discover new medicines and medical treatments.

Mike Derer/AP/Wide World Photos

Figure 3 A prosthetic “bionic” hand is new technology that can help extend human capabilities.

Improve agricultureSome biologists study the possibilities of genetically engineering plants to grow in poor soils or to resist insects, fungal infections, or frost damage. Other biologists research agricultural issues to improve food production to feed the world's growing human population.

Joanne Chory, a plant biologist shown in Figure 4, studies mustard plants' sensitivity to light and their responses when exposed to different light sources, different times of exposure, and other conditions. Because of her work with plant growth hormones and light, agriculturists might be able to increase the amount of food produced from crops or to grow crops in areas where they normally would not grow.

Salk Institute for Biological Studies

Figure 4 Joanne Chory, a plant biologist, researches how plants respond to light.

Preserve the environmentEnvironmental biologists seek to prevent the extinction of animals and plants by developing ways to protect them. Some biologists study the reproductive strategies of endangered species while they are in captivity. Other biologists work in nature preserves that provide safe places for endangered species to live, reproduce, and have protection against poachers.

Lee Anne Martinez is an ecologist who worked to protect the environment where outdoor toilets are common. She helped people in rural Africa construct composting toilets that use no water. The composted waste from the toilets can be added to soil to improve it for agricultural use.

 

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The Characteristics of LifeHave you ever tried to define the word alive? If you were to watch a grizzly bear catch a salmon from a river, you obviously would conclude that the bear and salmon are both alive. Is fire alive? Fire moves, increases in size, has energy, and seems to reproduce, but how does fire differ from the bear and salmon?

Over time and after many observations, biologists concluded that all living things have certain characteristics, as listed in Table 1. An organism is anything that has or once had all these characteristics.

(t to b) M.I. Walker/Photo Researchers, (2) Tom J. Ulrich/Visuals Unlimited, (3 4) Gary Meszaros/Visuals Unlimited, (5) Tom McHugh/Photo Researchers, (6) W. Wisniewski/zefa/CORBIS, (7) OSF/G.I. Bernard/Animals

Animals, (8) Ron Fehling/Masterfile, (9) Stephen J. Krasemann/Photo Researchers

Table 1 Characteristics of Living Organisms

Made of one or more cellsHave you ever had strep throat? It probably was caused by a group A streptococcal bacteria, such as the Streptococcus pyogenes shown in Figure 5. A bacterium is unicellular—it has just one cell—yet it displays all the characteristics of life just like a skin cell on your body or a cell in a plant's leaf. Humans and plants are multicellular—they have many cells.

Cells are the basic units of structure and function in all living things. For example, each heart cell has a structure that enables it to contribute to the heart's function—continually pumping blood throughout the body. Likewise, each cell in a tree's roots has a structure that enables it to help anchor the tree in the ground and to take in water and dissolved minerals from the surrounding soil.

Dr. Fred Hossler/Visuals Unlimited

Figure 5  Streptococcus pyogenes is a unicellular organism. It can infect the throat, sinuses, or middle ear.

Displays organizationThink of all the people in your high school building each day. Students, faculty, counselors, administrators, building service personnel, and food service personnel are organized based on the different tasks they perform and the characteristics they share. For example, the students are designated freshmen, sophomores, juniors, and seniors based on age and coursework.

Living things also display organization, which means they are arranged in an orderly way. The Paramecium in Table 1 is made up of one cell, yet that cell is a collection of organized structures that carries on life functions. Each of those structures is composed of atoms and molecules. The many cells that make up the robin chicks in Figure 6 also contain structures made of atoms and molecules. However, in multicellular organisms, specialized cells are organized into groups

that work together called tissues. These tissues are organized into organs, which carry on functions such as digestion and reproduction. Organ systems work together to support an organism.

Ron Fehling/Masterfile

Figure 6 In less than a month, these robin chicks grow and develop from helpless chicks to birds capable of flying.

Infer how the robins have developed in other ways.

Grows and developsMost organisms begin as one cell. Growth results in the addition of mass to an organism and, in many organisms, the formation of new cells and new structures. Even a bacterium grows. Think about how you have grown throughout your life.

Robin chicks, like those in Figure 6, cannot fly for the first few weeks of their lives. Like most organisms, robins develop structures that give them specific abilities, such as flying. Development is the process of natural changes that take place during the life of an organism.

ReproducesMost living things are the result of reproduction—the production of offspring. Reproduction is not an essential characteristic for individual organisms. Many pets are spayed or neutered to prevent unwanted births. Obviously, these pets can still live even though they cannot reproduce. However, if a species is to continue to exist, then members of that species must reproduce. A species is a group of organisms that can breed with one another and produce fertile offspring. If the individuals of a species do not reproduce, then when the last individual of that species dies, the species becomes extinct.

Responds to stimuliAn organism's external environment includes all things that surround it, such as air, water, soil, rocks, and other organisms. An organism's internal environment is all things inside it. Anything that is part of either environment and causes some

sort of reaction by the organism is called a stimulus (plural, stimuli). The reaction to a stimulus is a response. For example, if a shark smells blood in the ocean, it will respond quickly by moving toward the blood and attacking any organism present. Plants also respond to their environments, but they do so more slowly than most other organisms. If you have a houseplant and you place it near a sunny window, it will grow toward the window in response to the light. How does the Venus flytrap in Figure 7 respond to stimuli?

Being able to respond to the environment is critical for an organism's safety and survival. If an organism is unable to respond to danger or to react to potential enemies, it might not live long enough to reproduce.

Stephen J. Krasemann/Photo Researchers

Figure 7 In nature, this Venus flytrap grows in soils that lack certain nutrients. The plant captures and digests insects and takes in needed nutrients.

Explain how this plant responds to stimuli to obtain food.

Requires energyLiving things need sources of energy to fuel their life functions. Living things get their energy from food. Most plants and some unicellular organisms use light energy from the Sun to make their own food and fuel their activities. Other unicellular organisms can transform the energy in chemical compounds to make their food.

Organisms that cannot make their own food, such as animals and fungi, get energy by consuming other organisms. Some of the energy that an organism takes in is

used for growth, development, and maintaining homeostasis. However, most of the energy is transformed into thermal energy and is radiated to the environment as heat.

Maintains homeostasisRegulation of an organism's internal conditions to maintain life is called homeostasis (hoh mee oh STAY sus). Homeostasis occurs in all living things. If anything happens within or to an organism that affects its normal state, processes to restore the normal state begin. If homeostasis is not restored, death might occur.

When athletes travel to a location that is at a higher altitude than where they live, they generally arrive long before the competition so that their bodies have time to adjust to the thinner air. At higher altitudes, air has fewer molecules of gases, including oxygen, per unit of volume. Therefore, there is less oxygen available for an athlete's red blood cells to deliver to the cells and tissues, which disrupts his or her body's homeostasis. To restore homeostasis, the athlete's body produces more red blood cells. Having more red blood cells results in an adequate amount of oxygen delivered to the athlete's cells.

Gerry Ellis/Minden Pictures

Figure 8 The structure of a drip-tip leaf is an adaptation to rainy environments.

Adaptations evolve over timeMany trees in rain forests have leaves with drip tips, like the one shown in Figure 8. Water runs off more easily and quickly from leaves with drip tips. Harmful molds and mildews will not grow on dry leaves. This means a plant with dry leaves is healthier and has a better chance to survive. Drip tips are an adaptation to the rain forest environment. An adaptation is any inherited characteristic that results from changes to a species over time. Adaptations like rain forest trees with drip tips enable species to survive and, therefore, they are better able to pass their genes to their offspring.

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MiniLab: Observe Characteristics of Life1.A.i 2.E.i 2.E.v more

Is it living or nonliving? In this lab, you will observe several objects to determine if they are living or nonliving.

Procedure 1. Read and complete the lab safety form.

2. Create a data table with four columns titled Object, Prediction, Characteristic of Life, and Evidence.

3. Your teacher will provide several objects for observation. List each object in your table. Predict whether each object is living or nonliving.

4. Carefully observe each object. Discuss with your lab partner what characteristics of life it might exhibit.

5. Use Table 1 to determine whether each object is living or nonliving. List the evidence in your data table.

Analysis1. Compare and contrast your predictions and observations.

2. Explain why it was difficult to classify some objects as living or nonliving.

 CAREERS IN BIOLOGYBiology TeacherAn enthusiasm for biology is one of the many reasons people become biology teachers. Other than courses in biological sciences, prospective biology teachers might take classroom management, teaching methods, and other courses needed to develop teaching skills.

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Assessment11.A4.B.v

Lesson Summary Biologists study the structure and function of living things, their history,

their interactions with the environment, and many other aspects of life.

All organisms have characteristics that scientists use to determine whether the organisms are alive. All living organisms share these certain characteristics.

Understand Main Ideas

1. Describe four characteristics used to identify whether something is alive.

2. Explain why cells are considered the basic units of living things.

3. Define biology and state some of the benefits of studying it.

4. Differentiate between response and adaptation.

Think Critically

5. Survey students in your school—biology students and nonbiology students—and adults. Have participants choose characteristics of life from a list of various characteristics and rank their choices from most important to least important. Record, tabulate, average, and graph your results. Prepare a report that summarizes your findings.

Vocabulary Review

Replace the underlined phrase with the correct vocabulary term.

6. The production of offspring is a characteristic of life that enables the continuation of a species.

7. The internal control of mechanisms allows for an organism's systems to remain in balance.

8. The study of life involves learning about the natural world.

Understand Main Ideas

9. Which characteristic of life should be the title of the graph shown above?

A. Cellular BasisB. GrowthC. HomeostasisD. Reproduction

10. Which best describes adaptation?

A. reproducing as a speciesB. a short-term change in behavior in response to a stimuliC. inherited changes in response to environmental factorsD. change in size as an organism ages

Constructed Response

11. Open Ended What is the role of energy in living organisms? Is it a more or less important role than other characteristics of life? Defend your response.

Think Critically

12. Evaluate how the contributions made by Goodall, Chory, and Drew reinforce our understanding of the characteristics of life.

13. Compare and contrast a response and an adaptation. Use examples from your everyday world in your answer.

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